1. Field of the Invention
The present invention relates to a copper foil with an insulating adhesive, more particularly, a copper foil with an insulating adhesive for a multilayer printed circuit board equipped with an insulating adhesive layer having low dielectric constant, low dielectric loss tangent and high adhering force at a normal temperature and a high temperature as well as a copper foil on which a circuit can be formed by etching processing or the like.
2. Description of Related Art
In the recent progress of downsized, multifunctional, and higher advanced electronic equipments, a printed circuit board is required to respond to the high-density packaging. In response thereto, some progress has been made, such as the adoption of a multilayered printed board, a thinner insulating layer, the shift from a traditional through-hole to an inner via-hole, a reduced via diameter, and a narrower pitch of a circuit and the like. As an embodiment of them, there is the technology of manufacturing a build-up multilayer printed circuit board.
The fabricators manufacture the build-up wiring board according to a variety of ways. Many wiring board fabricators have adopted a method of manufacturing build-up wiring board using a copper foil with an insulating adhesive, because the materials are easy to handle and because the manufacturing steps can be shortened due to a conductor layer already formed on it. A variety of properties are required for these resins as insulating adhesive, particularly the high adhering strength at a normal temperature and a high temperature is required from a viewpoint of the electric reliance.
Furthermore, the higher speed of computer signal processing and the higher frequency of communication electric wave for mobile communication are expected to further progress from now on and, accordingly, it is desired that an insulating material for use in printed circuit boards having these utilities has the low dielectric constant and low dielectric loss tangent.
As an adhesive for use in the traditional copper foil with an insulating adhesive, an epoxy resin, a thermoplastic polyimide resin and the like are generally used widely.
A thermoplastic polyimide and epoxy adhesives are excellent in the resistance to heat, the resistance to chemicals, the dimensional stability, the adhering property and the like and are generally used widely as an insulating layer of a copper foil with an insulating adhesive. However, since these compounds have a functional group having the very high polarity such as an imide group, a hydroxy group and the like, a value of dielectric constant and that of dielectric loss tangent have generally become higher.
In order to improve these disadvantages, there is provided an adhesive composition using a silicon systempolymer(JP-A10-140127). However, even in this adhesive composition, there is still a problem that the adhering property at a high temperature is not sufficient. Thus, any insulating adhesive or copper foil with an insulating adhesive satisfying which fully satisfy the demands of the market these requirements can not be found, therefore, there is a great demand for them.
Accordingly, an object of the present invention is to provide a copper foil with an insulating adhesive in which an insulating adhesive excellent in various properties such as the high adhering property at a normal temperature and a high temperature, low dielectric constant and low dielectric loss tangent and a copper foil are incorporated, and which is easy to be handled, and which can shorten the steps due to a conductor layer already formed on it.
The present inventors studied intensively in order to solve such problems and, as a result, found that the aforementioned problems can be solved by incorporating an insulating adhesive composition having as an essential component an organic compound having at least two alkenyl groups having the reactivity with a SiH group in one molecule and a silicon compound having at least two SiH groups in one molecule with a copper foil, which resulted in the completion of the present invention.
That is, the present invention is a copper foil with an insulating adhesive in which an insulating adhesive comprises as an essential component
(A) an organic compound having at least two alkenyl groups having the reactivity with a SiH group in one molecule,
(B) a silicon compound having at least two SiH groups in one molecule, and
(C) a hydrosilylating catalyst, and a copper foil incorporated therewith.
Further, the component (A) is an organic compound containing alkenyl groups having the reactivity with a SiH group at0.001 mol or more per 1 g of (A) component.
A copper foil with an insulating adhesive of the present invention is excellent in that it can be used widely for manufacturing a multilayer printed circuit board, an insulating adhesive layer has low dielectric constant, low dielectric loss tangent and high adhering force at a normal temperature and a high temperature, and steps for manufacturing a multilayer printed circuit board can be shortened due to the presence of a copper foil on which a circuit can be formed by etching or the like.